porter



(No Model.)

0. T. PORTER.

STEAM ENGINE.

N0. 391,916. Patented Oct. 30, 1888.

ATEN if rerun...

STEAlVI ENGINE.

SPECIFICATION forming part of Letters Patent No. 391,916, dated October 301, 1888.

Application filed October 13, 1887. Serial No. 252,901. (No model.)

To rtZZ whom it may concern:

Be it known that l, CHARLES T. PORTER, of Schenectady, in the county of Schenectady and State of New York, have invented a certain new and useful Improvement relating to Steam-Engines, of which the following is a specification.

My improvement is intended for use with what are known as piston-valves. I will describe it as applied to the form of pistonvalvc set forth in the patent to me dated August 16, 1887, No. 368,422; but it may apply to other styles of piston-valves. I have devised a novel form of ports for use with such valves. The form reduces the amount of space in the alvepassages, and thus by well-known laws cconornizes the effect of the steam. Instead of obstructing the movement of the steam,the new form of port promotes it. The metal surfaces guide the current of steam continuously and smoothly to and from the valve, avoiding the concussions and regurgitations which the ordinary form involves. A piston valve should be worked as near the main cylinder as is practicable. That side of the valve presented toward the main cylinder finds, of course, a liberal area of port communicating with the cylinder and delivers and receives steam directly. My invention has no effect on that side. The other side of the pistonvalve-dhat farthest from the cylindcr in order to be of any effect, re quires that theport shall be extended around. It is common to do so. I havein my said patent of August, 1887, shown the port as thus extended around but contracted. in breadth on the side opposite to the cylinder. Still, cverywhere the portin my said patent presents a Surface nearly at right angles to the radial movement of the steam as it moves outward from the piston-valve in the induction of steam into the cylinder, oriinward into the same valve in exhausting from the cylinder.

My present improvement is carried out by giving a \vedgeshaped form to the metal surface exterior to the port on the side opposite to the cylinder. Preferably the angle of the wedge lies a little outside of the periphery of the valve. I will represent it as thus carried out; but there maybe a little license in this regard-that is to say, the apex of the wedge may coincide exactly with the periphery ofthe piston-valve, or not, as is preferred.

The accompanying drawings form a part of this specification and represent what I consider the best means of carrying out the in vention as applied to an upright engine.

Figure l is a central vertical section through the main cylinder,valve-chest,aud ports. Fig. 2 is a cross section on the line cc :0 in Fig. 1; and Fig. 3 is a crosssection through a portion on a larger scale, showing by lines the man ner in which the steam is reflected. or deflected by the metal which forms the exterior surface of the port.

Similar letters of reference indicate corresponding parts in all the iigures'where they occur.

A A are the piston-valves working in corresponding cylindrieal valve-seats and connected by a valve stem, E. The metal of the cylinder and valve-chest is marked M, an ad ditional mark, M, being applicd'to designate that portion of the valve-chest farthest from the cylinder. The ports are marked at. It is usual to make these ports nearly concentric to the valve-chest, thus presenting the inner surfaces, so as to reflect the steam backward upon itself and greatly retard its flow. The steam issuing into the port radially all around, it follows that at the back it issues in a direction opposite to that in which it must go to reach the cylinder. If, as usual, the back of the port is a surface concentric with the valve, or nearly so, the steam is reflected straight back where it came from. The port is thus choked, so that considerable of this part of a pistonvalve is of but little use for the admission and discharge of the steam. My form,on the contrary,causes the steam to be reflected, so as not to choke the issuing steam in the least. This reflection is shown at three points, 1 2 3. The angle of reflection is equal to the angle of incidence. The line of incidence is the radial line. The line of reflection is determined in this way: the angle included between these two lines is bisected by a line perpendicular to the surface at that point. ports adds materially to the efficiency of the piston-valve.

Although I have described the invention as applied to steamcngines, it will be understood This form of the- IO valve unobstructed, as herein specified.

that it may apply to engines worked by air or other gases or fiuid's.

I claim as my invention-- In an engine having a piston valve or valves In testimony whereofi have hereunto set my and aeorrespondmg cylindrical valve-seat, 1

hand,at Schenectady, this 3d day of October, 1887, in the presence of two subscribing wit nesses.

the ports m, formed, as shown, so as to present the angle of a wedge toward the valve and adapted to divide the current of steam while keeping the whole circumference of the CH AS. T. PORTER.

Witnesses:

SAMUEL INsULL, 1-3. M. TATE. 

